Model F Up Relay Replacement

[MBDiagMan]

Need to replace the landing gear UP relay.  It appears that the bolt comes down from the top with the nut on the bottom.  Will I need to remove carpet in order to hold the bolt while removing and replacing the nut or is it a stud that is held captive?

Thanks for sharing your experience with this.

[MBDiagMan]

Well I got the relay in without having to back up the bolt from above.  The relay didn’t fix the problem though.  It still chatters.:)

[Yetti]

On 11/5/2019 at 11:27 AM, MBDiagMan said:

Well I got the relay in without having to back up the bolt from above.  The relay didn’t fix the problem though.  It still chatters.:)

The gear chatters?  There is a brake on the back of the motor (at least the ITT Actuator) that should prevent the chatter

[MBDiagMan]

No, the relay chatters.  It’s not getting enough voltage/current to hold it in.  There is apparently a weak link in the coil circuit.

[larryb]

Or it chatters because of a high load on the output. Kinda like a weak car battery causes the starter solenoid to chatter. But if the output were shorted you would expect the CB to pop. Can you give us mote detail?

[Yetti]

On 11/7/2019 at 3:33 PM, MBDiagMan said:

No, the relay chatters.  It’s not getting enough voltage/current to hold it in.  There is apparently a weak link in the coil circuit.

At the top of the gear swing or all the way through the gear swing?

[MBDiagMan]

There is no gear swing.  The relay chatters but there is no gear movement.  There is not enough energy in the relay coil circuit to make contacts engage solid enough to power the actuator.

[MBDiagMan]

Yes larryb it is like a car starter relay with a low battery.  I am unable to work with it again until Monday at the earliest.

[larryb]

Try disconnecting the load and activate the relay and see if it still chatters.

[Yetti]

On 11/9/2019 at 6:13 AM, MBDiagMan said:

There is no gear swing.  The relay chatters but there is no gear movement.  There is not enough energy in the relay coil circuit to make contacts engage solid enough to power the actuator.

Generally I have found that is a wiring switch issue.   Solenoids generally work or they don't.   The solenoid that is used down there is starter level rated.   Mine is the same that it is used on a Ford 8N tractor.    I only have 1 so there is some switch of positive and negative up stream somewhere.  The colored wires go to the actuator.   The fourth terminal is positive and is used for the brake on the back of the motor.